This invention relates to a temperature, pulse and respiration detector. More particularly, this invention relates to a combined temperature, pulse and respiration detector in which a patient's oral temperature and pulse and respiration rates can be determined simultaneously.
It is well known to use a temperature sensor such as a thermocouple to sense oral temperature or to measure the changes of temperature between inspired and expired air and thereby detect respiration. However, suitable means for simultaneously detecting oral temperature and respiration by means of the temperature difference betwen inspired and expired air has not been developed.
It is also well known to use electrodes for detecting the electrical activity of the heart for the purpose of obtaining an electrocardiogram (ECG) and for measuring heart rate. With each heart beat, an electrical impulse passes through the heart resulting in the rhythmic contraction of the heart muscle. As the impulse passes through the heart, electrical currents spread into the tissue surrounding the heart, and a small portion of these spread all the way to the surface of the body. If electrodes are placed on the body on opposite sides of the heart, the electrical potentials generated by the heart can be sensed and recorded.
The ECG waveform contains several distinct characteristics generally labeled P, Q, R, S and T. Each ECG waveform represents one heart beat. The QRS portion or "R-wave" is the portion of the waveform normally used to trigger heart rate monitors. The R-wave has high amplitude and short duration and is made up of the highest frequency componets of the ECG waveform. Accordingly, the R-wave can be further accentuated over the P and T waves by the use of a high pass filter or waveform differentiation circuit. The heart rate is then derived from the time duration between R-waves.
Metal plates are typically used as the electrodes for detecting the electrical activity of the heart. These electrode plates are normally strapped to various parts of the body with some type conductive paste or gel applied to the skin under the plate. Other forms of electrodes include metal dust and adhesive coated on the body with a lead wire embedded therein. In either case, however, the mounting of the electrodes on the body is time consuming and unpleasant for the patient.
The simultaneous detection of temperature, pulse and respiration is highly desirable since it results in considerable time saving and a reduction in hospital costs. Prior art systems have been developed for simultaneously sensing these three parameters but these systems typically employ the use of a transducer assembly attached to the body. These prior art systems are complex since they employ devices which must be semi-permanently attached to the body and do not lead to savings in time or reduction in hospital operating costs.